Heartland Virus in Humans and Ticks, Illinois, USA, 2018–2019

Holly C. Tuten; Kristen L. Burkhalter; Kylee R. Noel; Erica J. Hernandez; Seth Yates; Keith Wojnowski; John Hartleb; Samantha Debosik; April Holmes; Christopher M. Stone


Emerging Infectious Diseases. 2020;26(7):1548-1552. 

In This Article


One year after 2 cases in humans were detected, HRTV was detected in A. americanum ticks collected from the suspected exposure locations in Illinois. Because of abundant suitable habitat and established A. americanum tick populations,[10] it is notable but predictable that this pathogen emerged in southern Illinois. The density of and HRTV detection in A. americanum ticks at the northern edge of their distribution range in Kankakee County was unexpected. Our findings suggest that A. americanum ticks are established along their northern distribution range at high densities. Consequently, diseases associated with A. americanum ticks must be on the radar of physicians and public health officials throughout Illinois.

Detection of HRTV in adult A. americanum ticks suggests that infected ticks may have overwintered in the area and maintained HRTV infection transstadially. The presence of HRTV in adult male, but not female or nymph, ticks was also reported in a study in Kansas, where the infection rate varied from 3.29 to 8.62/1,000 ticks,[15] similar to our findings. Additional tick collection efforts and wildlife serosurveys will help assess whether transmission cycles are active in Illinois and enhance our knowledge of the transmission ecology of this rare pathogen.